The invention relates to an arrangement for production of explosively formed projectiles including a casing with explosive contents, a fuse located on the base side and a metal insert covering the explosive contents on the head side.
Devices of this type are also called hollow charges in a very simple version. A hollow charge consists of the aforementioned parts in which case the casing is a round cylinder. The effect of a hollow charge of this type consists of the following. When the explosive is ignited the insert is broken down into individual particles which then fly toward the target in the manner of a projectile. All efforts with these hollow charges are directed at obtaining material particles which strike the target with maximum possible energy. In practice this is achieved as follows (for example DE-AS No. 19 10 779). By means of appropriate shaping of the insert it is broken down to several small particles, the so-called "jet" and into one or more large particles, the so-called "ram". This insert, for example, is shaped in the manner of a round roof. A smaller number of larger oblong particles should also be produced by virtue of the fact that the round roof shaped disk features a concentric predetermined breaking point.
The desire to build oblong projectiles of large mass which incorporate on the one hand favorable flight properties, on the other hand correspondingly high impact energy, has led to consideration of forming the insert from a composite material, consisting, for example, in its center of a relatively heavy material, steel over most of its area and aluminum in the edge region. With the appropriate layout of the explosive contents this insert can be formed into a single longitudinal projectile similar to a bullet, e.g., it features a rounded nose, and a following cylindrical or slightly conical oblong section. The tail of this projectile is disk shaped. This projectile flies in a satisfactory manner to the target, however does not exhibit great impact energy since the air resistance is unfavorable due to the disk-like tail and thus the projectile loses a considerable amount of velocity in flight.
The aim underlying the invention resides in providing an arrangement of the aforementioned type such that explosive projectiles are produced with faultless and reproducible flight properties and which strike the target in an optimum configuration with small loss of velocity.
This is achieved as follows. The insert and/or the explosive contents and/or the fuse in their external region and/or the casing on a jacket thereof include at least three inhomogeneities arranged on a circle at a distance from the axis of the casing such that, in the circumferential region of the insert, varied acceleration is achieved corresponding to the configuration of the inhomogeneities or the time of impact of the shock wave or impact energy is different.
The invention proceeds initially from the fact that a projectile obtained by explosive forming exhibits faultless flight properties only if efforts are made to achieve those preferred directions for the deformation process on the insert which lead to forming at different times so that it is permanently ensured that adjacent areas of the insert are not formed simultaneously, but rather in succession or with different accelerations. If this rule is followed it can be assumed that in the course of the forming process unobserved accumulations, upsetting or overlapping of the material do not occur which would lead to fraying of the tail. Based on this finding the general principle of the invention consists in the following. The parts which comprise the device each exhibit inhomogeneities for themselves or in combination at specific sites near the circumference which result in the fact that the shock wave produced by the explosive contents does not react on the varied mass coating on the insert either at the same time or with the same impact energy on the entire insert, but at specific and symmetrically arranged points in the area of the insert near the circumference at different times or with different impact energy. This achieves the following. The areas where the shock wave arrives earlier or with greater impact energy are deformed first and the other areas afterward. If the inhomogeneity consists in a varied mass coating, the areas of lower mass are shaped with greater acceleration than the areas lying in between. This principle can be realized by the corresponding symmetrically arranged inhomogeneities on the insert itself, on the explosive contents, the fuse or ultimately even on the casing. Inhomogeneities on the insert lead primarily to different forming rates of the same. Inhomogeneities of the explosive contents lead to different impact energies on the insert. The same applies to inhomogeneities on the fuse which however also lead to different impact times. Finally inhomogeneities in the casing lead to varied damming upon detonation and thus to different impact energies on the insert.
Preferably, according to the present invention the insert features essentially radially deformations arranged in the circumferential region as inhomogeneities which can be formed, for example, as wave profiles of small height. In this case profiles preferably in the tenth of a millimeter range are involved. Instead or in addition the deformations can be formed by increasing the density of the material.
In another design which may also be intended for deformations if necessary, the insert features essentially radially points with different wall thickness arranged in a circumferential area. These wall thickness differences extend preferably into the tenth of a millimeter range. In these cases approximately radial inhomogeneities are provided in the insert which results in the fact that the insert deforms in a specific and symmetrical manner upon impact of the shock wave. Practical studies have shown that projectiles can be obtained in this way which feature rounded nose, a longer, approximately cylindrical section and a uniform longitudinal fold on the tail in which case the number of folds corresponds exactly to the number of inhomogeneities present. The depth and shape of the folds can be influenced within wide limits by lengthening of the inhomogeneities. These folds act as stabilizing rings in flight. Practical tests have demonstrated outstanding flight properties in that the projectile is aligned with its longitudinal axis in the flight path and also maintains this position. A slight inclination when the projectile leaves (which cannot be avoided) is stabilized after some oscillating motions with a slight deflection so that almost any projectile strikes the target in the desired flight attitude. Forming of wings is also responsible for considerably less loss of speed so that a corresponding high impact energy is available.
An equally beneficial effect can be achieved as per another version as follows. Explosive contents feature varied explosive coating arranged symmetrically in the circumferential area as inhomogeneities. Here this symmetrically varied coating can be achieved by explosives of different types or the same explosive in different concentrations. This leads to different impact times and/or impact energies on the insert so that the insert is first shaped in the preferred directions and afterwards in another region.
The same effect can be achieved in another version as follows. The explosive contents feature symmetrical guides arranged symmetrically in the casing as inhomogeneities which deflect the shock wave in a correspondingly symmetrical form to specific areas of the insert and/or also dam the shock wave at correspondingly symmetrical points.
In another version the fuse exhibits ignition points arranged symmetrically in the circumferential area with lower ignition energy and/or delayed ignition timing. This again leads to the fact that the shock wave reaches the corresponding symmetrically arranged points on the insert according to the arrangement of the ignition points or their time delay at different times.
Finally, according to another version, the casing can exhibit wall thickness which varies in a symmetrical configuration as inhomogeneities. This varying wall thickness leads to varied lateral damming of the explosive and thus to different departure velocity of the coating. The coating is slower at points of lower wall thickness than at the more heavily dammed points on the casing. Since this varied damming is effective primarily in the circumferential area, this measure tells only in the circumferential area of the insert, as designed.
A version of this principle of especially simple production technology consists in forming the casing as a round cylinder on the inside and a multiple sided figure on the outside.
The principle of the invention can be further developed by the following. The inhomogeneities protrude to varying degrees, however, at least two inhomogeneities of the same degree of protrusion are present and are symmetrically arranged.
This additional principle of the invention leads to the fact that the folds which form on the tail of the projectile are of varied depth, therefore they form wings of varied width. The symmetrical configuration of at least two such inhomogeneities of different amounts of projection however guarantees that again a structure of wings symmetrical to the projectile axis is obtained.
Finally, according to another feature of the invention, the inhomogeneities can be formed asymmetrically, in which case however they exhibit completely identical asymmetry. This design leads to the fact that within each inhomogeneity preferred directions are fixed with the result that deformation of the insert in the area of each inhomogeneity does not take place absolutely simultaneously, but at slightly different times or with slightly different impact energy or ultimately with different acceleration. On the explosively formed projectile this is manifested by the fact that the folds on the tail are not formed parallel to the axis of the projectile, but acquire a slope. Sloped wings in which capacity the folds act here, can impart to the projectile a stabilizing angular momentum.